太阳能热发电系统中的水消耗问题研究

以明置于室内地面上的大型直流电压发生器塔架结构的抗震计算为例,分别计算结构在正弦共振调幅5波、正弦共振3波、El Centro地震波、Taft地震波和云南澜沧地震波5种激励下的响应,讨论了输入不同地震波对结构地震反应的影响及不同Rayleigh阻尼模型下的动力响应特性,最后对这类结构的输入地震动及Rayleigh阻尼模型的选择提出建议。     

自然灾害风险分析的信息矩阵方法

从致灾因子危险性分析，到伤亡和损失的可能性研究，自然灾害风险分析由4个环节组成，即致灾因子、承灾体输入、承灾体输出和社会系统。在大多数据情况下，风险事件的不确定性，主要来自于致灾因子时间、地点、强度的不确定。因此，自然灾害风险分析主要涉及两类模式识别：致灾因子概率分布识别和承灾体系统输入-输出关系识别。由于概率分布和输入-输出关系在数学上均可用函数表达，所以，自然灾害风险分析涉及的两类模式识别，均是函数关系的识别。给出了用信息矩阵识别这些函数关系的方法。为演示该方法的优点，用它处理了在我国得到的地震数据，识别了震中烈度与震级的关系。结果表明，得到的结果比线性回归、基于正态分布的模糊推理和人工神经元网络等的结果好。     

基于PMF模型的宁南山区小流域土壤重金属空间分布及来源解析

为探明宁南山区小流域土壤重金属污染分布特征及主要污染源,确保土壤环境质量.采集并测定了 260个表层(0～20 cm)土壤样品重金属Pb、Ni、Zn、Mn、Cu、Cr和Cd.基于宁夏土壤背景值,通过单因素和Nemera综合指数评价土壤重金属污染现状,使用潜在生态风险指数对生态环境风险水平进行评价,利用正定矩阵因子分析法...     

河口区溶解有机物三维荧光光谱的平行因子分析及其示踪特性

利用激发发射矩阵荧光光谱(EEMs)并结合平行因子分析(PARAFAC),研究了九龙江口有色溶解有机物(CDOM)的荧光组分特征及其河口动力学行为,并探讨其作为河口区有机污染示踪指标的可行性.利用PARAFAC模型识别出九龙江口CDOM由2类4个荧光组分组成,即类腐殖质荧光组分C1(240,310/382nm)、C2(230,250,340/422nm)、C4(260,390/482nm)及类蛋白质荧光组分C3(225,275/342nm).模型结果表明,传统寻峰法指认的短波类腐殖质A峰区域(240～290/380～480nm)实际上并非一个单独的荧光峰,而是若干荧光组分的组合,并且它与传统上指认的长波区海源类腐殖质M峰、陆源类腐殖质C峰之间存在内在联系.包含M峰的C1组分在河口区随盐度增加呈稀释降低趋势,表明M峰并不能被认为是海洋来源的专有特征峰.类腐殖质组分C1和C2在盐度6的河口最大浑浊带区表现出一定的添加行为,之后在河口混合过程中呈保守行为,而类腐殖质荧光组分C4则在整个河口混合过程中都呈保守行为.类蛋白质荧光组分C3在河口混合过程中呈不保守行为,并且在总荧光组分中所占比例在高盐度区呈上升趋势.EEM-PARAFAC不仅可示踪九龙江不同支流DOM的特征,并且还可很好地示踪九龙江口的有机污染程度.     

Quantifying the burden of managing wildlife diseases in multiple host species

Mitigation of infectious wildlife diseases is especially challenging where pathogens affect communities of multiple host species. Although most ecological studies recognize the challenge posed by multiple-species pathogens, the implications for management are typically assessed only qualitatively. Translating the intuitive understanding that multiple host species are important into practice requires a quantitative assessment of whether and how secondary host species should also be targeted by management and the effort this will require. Using a multiple-species compartmental model, we determined analytically whether and how intensively secondary host species should be managed to prevent outbreaks in focal hosts based on the reproduction number of individual host species and between-species transmission rates. We applied the model to the invasive pathogenic fungus Batrachochytrium salamandrivorans in a 2-host system in northern Europe. Avoiding a disease outbreak in the focal host (fire salamanders [Salamandra salamandra]) was impossible unless management also heavily targeted the secondary host (alpine newts [Ichthyosaura alpestris]). Preventing an outbreak in the community required targeted removal of at least 80% of each species. This proportion increased to 90% in the presence of an environmental reservoir of B. salamandrivorans and when the proportion of individuals removed could not be adjusted for different host species (e.g., when using traps that are not species specific). We recommend the focus of disease-mitigation plans should shift from focal species to the community level and calculate explicitly the management efforts required on secondary host species to move beyond the simple intuitive understanding that multiple host species may all influence the system. Failure to do so may lead to underestimating the magnitude of the effort required and ultimately to suboptimal or futile management attempts.     

Effects of landscape transformation on bird colonization and extinction patterns in a large‐scale,long‐term natural experiment

Conversion of agricultural land to forest plantations is a major driver of global change. Studies on the impact of forest plantations on biodiversity in plantations and in the surrounding native vegetation have been inconclusive. Consequently, it is not known how to best manage the extensive areas of the planet currently covered by plantations. We used a novel, long‐term (16 years) and large‐scale (30,000 ha) landscape transformation natural experiment (the Nanangroe experiment, Australia) to test the effects of land conversion on population dynamics of 64 bird species associated with woodland and forest. A unique aspect of our study is that we focused on the effects of plantations on birds in habitat patches within plantations. Our study design included 56 treatment sites (Eucalyptus patches where the surrounding matrix was converted from grazed land to pine plantations), 55 control sites (Eucalyptus patches surrounded by grazed land), and 20 matrix sites (sites within the pine plantations and grazed land). Bird populations were studied through point counts, and colonization and extinction patterns were inferred through multiple season occupancy models. Large‐scale pine plantation establishment affected the colonization or extinction patterns of 89% of studied species and thus led to a comprehensive turnover in bird communities inhabiting Eucalyptus patches embedded within the maturing plantations. Smaller bodied species appeared to respond positively to plantations (i.e., colonization increased and extirpation of these species decreased in patches surrounded by plantations) because they were able to use the newly created surrounding matrix. We found that the effects of forest plantations affected the majority of the bird community, and we believe these effects could lead to the artificial selection of one group of species at the expense of another.     

The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process.     

Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors

In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH₄–N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded.We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production.     

基于生态安全约束的再生利用项目规划设计方案决策

为确保我国旧工业建筑(区)再生利用项目方案设计阶段免受生态破坏与环境污染等因素的影响,提出了"生态安全约束"这一概念。考虑到决策者面对收益和损失的不同态度引入了前景理论,建立了生态安全约束下基于前景理论再生利用项目规划设计方案决策模型。首先,构建了包含总体规划、建筑设计、传承保护等因素的决策指标体系,并采用AHP与熵权相结合的方法计算权重,使得权重计算结果不仅体现了决策者的主管意愿,也反映了再生利用项目的客观规律;其次,以决策者预期值作为参考点给出期望矢量,将不同属性的决策数据信息规范化处理得初始决策矩阵,再根据指标间相对参考点的差值建立前景决策矩阵,通过计算各方案的综合前景值以确定最优方案。最后,通过北京首钢、云南871、陕西老钢厂、太原锅炉厂等5个实例的再生利用项目规划设计方案决策过程加以验证。结果表明,模型计算过程清晰,结果可信度高,验证了模型的合理性和科学性,可为规划设计阶段有效控制生态环境破坏与厂区环境污染提供新的思路。